Synergistic effect of a crystal modifier and screw dislocation step defects on the formation mechanism of nickel micro-nanocone

2019 ◽  
Vol 245 ◽  
pp. 68-72 ◽  
Author(s):  
Ehsan Rahimi ◽  
Ali Rafsanjani-Abbasi ◽  
Amin Imani ◽  
Ali Reza Kiani Rashid ◽  
Saman Hosseinpour ◽  
...  
2020 ◽  
Vol 7 (3) ◽  
pp. 216-221
Author(s):  
Mengmeng Li ◽  
Shuang Huang ◽  
Hang Zhang ◽  
Lei Wang ◽  
Shengliang Zhong

Background: Researchers have pursued the new synthesis method. As a newly developed method, microwave (MW), ultrasound (US) and ultraviolet light (UV) assisted synthesis has drawn increasing interests. Under the synergistic effect, many materials with new structure, morphology and properties may be found. As an important rare-earth phosphate, DyPO4 was selected and the effect of MW, US and UV on the preparation was investigated. Method: The DyPO4·1.5H2O nanostructures were prepared by MW, US, UV and their combination. Results: Hexagonal DyPO4·1.5H2O microcrystals obtained under MW irradiation were broomstick bundles. Needle-shaped products were formed in the presence of MW and US. Interestingly, the broom-sheaf-like structures can self-assemble into flower-shaped structures upon the irradiation of MW and UV. Whereas, MW/UV/US synergetic heating results in mixed morphologies of flower-like and needle-shaped structures. Conclusion: The growth of DyPO4 nanostructures can be tuned by selecting the combination of heating method of MW, US and UV.


Author(s):  
E. L. Thomas ◽  
S. L. Sass

In polyethylene single crystals pairs of black and white lines spaced 700-3,000Å apart, parallel to the [100] and [010] directions, have been identified as microsector boundaries. A microsector is formed when the plane of chain folding changes over a small distance within a polymer crystal. In order for the different types of folds to accommodate at the boundary between the 2 fold domains, a staggering along the chain direction and a rotation of the chains in the plane of the boundary occurs. The black-white contrast from a microsector boundary can be explained in terms of these chain rotations. We demonstrate that microsectors can terminate within the crystal and interpret the observed terminal strain contrast in terms of a screw dislocation dipole model.


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